Scalaz (Scar-lah-zed) is a library written in the Scala Programming Language. One mandate of the library is to depend only on the core Scala API and the core Java 2 Standard Edition API. The intention of Scalaz is to include general functions that are not currently available in the core Scala API. Scalaz is released under a BSD open source licence making it compatible with the licence of the Scala project.

Scalaz has recently (December 2009) undergone a rewrite for a planned version 5 release coinciding with the upcoming Scala 2.8.0 release. Much of what was included in previous versions is still available however, it is better organised.

Links

• Scalaz 5 regular builds

Detailed features of Scalaz 5

• An implementation of common type-classes
• Equal - for doing type-safe (and configurable) equality checks
• Show - for type-safe configuration of display for types (like Java's toString but with a compile-time check for existence and easier to use)
• Order - type-safe comparisons for ordering

• An integration of useful libraries for the ScalaCheck library

• A usable implementation of John Hughes' arrows for doing abstraction gymnastics with first-class functions

• An implementation of Applicative Functors as per Applicative Programming with Effects for a more powerful (more general) monad

• An implementation of a covariant binary functor (scalaz.Bifunctor) for mapping over either (or both) side of a pair or scala.Either

• A Burkhard-Keller tree for fast approximation-based searches -- ever wondered why Google knows what you really meant, so quickly? Here is a great explanation of a B-K Tree

• An implementation of a contra-variant functor and comonad

• A first-class continuation type

• A Digit data type (0-9)

• A monad and functor "type-class" with associated implementation and methods

• Kleisli and Co-Kleisli data types and subsequent useful operations

• A data type for representing one or more elements of the same type (NonEmptyList) and so guarantees successful termination of head, tail and other operations

• A data type for representing elements of the same type (DList) with constant time append/prepend operations.

• A monoid type-class and (so many!) implementations

• A data type for representing state transition through a value i.e. a function: S => (S, A)

• An implementation of an internal iterator as per The Essence of the Iterator Pattern using a traversable type-class (scalaz.Traverse)

• A multi-way tree (rose tree) and a one-hole zipper (TreeLoc) for tree traversal.

• A pointed list (zipper list) data type

• A memoisation library for automatically storing the result of computations (especially useful for Dynamic Programming Algorithms)

• A light-weight and highly configurable concurrency library with actors and non-blocking composable future values (Promise). Presentation

• Wrappers for existing library types to provide additional useful methods
• Array[Byte]
• BigInteger
• Boolean
• Byte
• Char
• Int
• forall A. Iterable[A]
• forall A. List[A]
• Long
• forall A. Option[A]
• Short
• forall A. Stream[A]
• String

Obtaining Scalaz through SBT or Maven

We are periodically publishing snapshots to the Scala Tools repository.